In the present study we used the primary cultures of chick embryonic muscle and liver cells as a model for potential mutual combination effects of leptin and insulin, respectively. The influence of both hormones on the proliferation and protein synthesis was dose-dependent and related to the age of embryos from which the cells were isolated. Leptin (10 and 100 ng/well) increased the proliferation (estimated by DNA content and incorporation of labeled thymidine into DNA) and protein synthesis (determined by incorporation of labeled leucine into proteins) of muscle cells. The effect of leptin and insulin in muscle cells was similar. In younger embryo (11-day-old) the lower dose of leptin was more effective than the higher one compared to the insulin effect. Mutual effects of leptin and insulin were neither additive nor synergistic and were equivalent to the effects of individual hormones. In hepatocytes the influence of leptin was dependent on the age at which the cells were isolated (11- and 19-day-old embryos). The presence of insulin neither potentiated nor inhibited the effect of leptin., D. Lamošová, M. Zeman., and Obsahuje bibliografii
The miniature excitatory postsynaptic currents (MEPCs) of the muscle cells of the earthworm Lumbricus terrestris were recorded by glass microelectrodes. In a single synaptic zone, three types of MEPC were recorded: a fast single-exponential type that decayed with τ=0.9 ms, a slow single-exponential with τ=9.2 ms and a two-exponential MEPC with τ = 1.3 and 8.5 ms, respectively. The muscle cells of earthworms contain populations of yet-unidentified ionic channels that might be different from the common nicotinic and muscarinic groups of acetylcholine receptors, since these MEPCs are not sensitive to d-tubocurarine, atropine, benzohexonium or proserine. Alternatively, besides ACh receptors, the membrane may contain receptors for an other yet-unidentified excitatory transmitter., E. M. Volkov, L. F. Nurullin, E. Nikolsky, F. Vyskočil., and Obsahuje bibliografii a bibliografické odkazy
Inherited disturbances of the mitochondrial energy generating system represent a heterogeneous group of disorders associated with a broad spectrum of metabolic abnormalities and clinical symptoms. We used the polarographic and spectrophotometric method for detection of mitochondrial disorders, because these two techniques provide a different insight into mitochondrial function. In six patients suspected of mitochondrial disease we found defects of complex I (two patients), complex III (one patient), complex IV (two patients) and a combination of defect of complex III and IV (one patient). Citrate synthase activity, used as the reference enzyme, was not changed. A comparison of the two methods showed several differences in evaluation of mitochondrial enzymes activity due to the fact that both methods used different conditions for enzyme activity measurements. In contrast to oxygen consumption measurements, where the function of the whole-integrated respiratory chain is characterized, spectrophotometric measurements characterize activities of isolated complexes in disintegrated membranes. However, it may be concluded from our experiments that both methods provide useful and complementary data about mitochondrial energetic functions. Whereas spectrophotometric data are suitable for evaluation of maximal enzyme activities of mitochondrial enzyme complexes, polarographic data provide better information about enzyme activities in cells with mitochondrial defects under in situ conditions., L. Wenchich, Z. Drahota, T. Honzík, H. Hansíková, M. Tesařová, J. Zeman, J. Houštěk., and Obsahuje bibliografii